sed从文件中删除代码块

Question

我想从默认的nginx配置服务器配置文件中删除server {...}代码块。

sudo sed -i '/(\s*#?)server \s*{(?:[\s\S]+)\1}/ d' /opt/nginx/conf/nginx.conf

产生sed: -e expression #1, char 33: Invalid back reference

但是使用工具，如Rubular比赛的作品就好了。基本上我需要做的是匹配基于匹配缩进的代码块，否则将删除太多。

---

您可以Rubular使用默认测试这个自己nginx的配置作为测试字符串：

#user nobody; 
#Defines which Linux system user will own and run the Nginx server 

worker_processes 1; 
#Referes to single threaded process. Generally set to be equal to the number of CPUs or cores. 

#error_log logs/error.log; #error_log logs/error.log notice; 
#Specifies the file where server logs. 

#pid  logs/nginx.pid; 
#nginx will write its master process ID(PID). 

events { 
    worker_connections 1024; 
    # worker_processes and worker_connections allows you to calculate maxclients value: 
    # max_clients = worker_processes * worker_connections 
} 


http { 
    include  mime.types; 
    # anything written in /opt/nginx/conf/mime.types is interpreted as if written inside the http { } block 

    default_type application/octet-stream; 
    # 

    #log_format main '$remote_addr - $remote_user [$time_local] "$request" ' 
    #     '$status $body_bytes_sent "$http_referer" ' 
    #     '"$http_user_agent" "$http_x_forwarded_for"'; 

    #access_log logs/access.log main; 

    sendfile  on; 
    # If serving locally stored static files, sendfile is essential to speed up the server, 
    # But if using as reverse proxy one can deactivate it 

    #tcp_nopush  on; 
    # works opposite to tcp_nodelay. Instead of optimizing delays, it optimizes the amount of data sent at once. 

    #keepalive_timeout 0; 
    keepalive_timeout 65; 
    # timeout during which a keep-alive client connection will stay open. 

    #gzip on; 
    # tells the server to use on-the-fly gzip compression. 

    server { 
     # You would want to make a separate file with its own server block for each virtual domain 
     # on your server and then include them. 
     listen  80; 
     #tells Nginx the hostname and the TCP port where it should listen for HTTP connections. 
     # listen 80; is equivalent to listen *:80; 

     server_name localhost; 
     # lets you doname-based virtual hosting 

     #charset koi8-r; 

     #access_log logs/host.access.log main; 

     location/{ 
      #The location setting lets you configure how nginx responds to requests for resources within the server. 
      root html; 
      index index.html index.htm; 
     } 

     #error_page 404    /404.html; 

     # redirect server error pages to the static page /50x.html 
     # 
     error_page 500 502 503 504 /50x.html; 
     location = /50x.html { 
      root html; 
     } 

     # proxy the PHP scripts to Apache listening on 127.0.0.1:80 
     # 
     #location ~ \.php$ { 
     # proxy_pass http://127.0.0.1; 
     #} 

     # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000 
     # 
     #location ~ \.php$ { 
     # root   html; 
     # fastcgi_pass 127.0.0.1:9000; 
     # fastcgi_index index.php; 
     # fastcgi_param SCRIPT_FILENAME /scripts$fastcgi_script_name; 
     # include  fastcgi_params; 
     #} 

     # deny access to .htaccess files, if Apache's document root 
     # concurs with nginx's one 
     # 
     #location ~ /\.ht { 
     # deny all; 
     #} 
    } 


    # another virtual host using mix of IP-, name-, and port-based configuration 
    # 
    #server { 
    # listen  8000; 
    # listen  somename:8080; 
    # server_name somename alias another.alias; 

    # location/{ 
    #  root html; 
    #  index index.html index.htm; 
    # } 
    #} 


    # HTTPS server 
    # 
    #server { 
    # listen  443 ssl; 
    # server_name localhost; 

    # ssl_certificate  cert.pem; 
    # ssl_certificate_key cert.key; 

    # ssl_session_cache shared:SSL:1m; 
    # ssl_session_timeout 5m; 

    # ssl_ciphers HIGH:!aNULL:!MD5; 
    # ssl_prefer_server_ciphers on; 

    # location/{ 
    #  root html; 
    #  index index.html index.htm; 
    # } 
    #} 

} 

Answer 1

sed不允许正则表达式来跨越多行，所以你需要使用多个命令实现你想要的，例如是这样的：

'/(\s*#?)server\s*\{/,/\1\}/d' 

但不幸的是sed的不允许回到以前的正则表达式的引用，因此上述不起作用。

Answer 2

这里有几件事。

首先，默认情况下，sed使用BRE作为其正则表达式格式。您需要在BRE中编写正则表达式，或者您需要使用sed选项来告诉它解释ERE。该选项将取决于您的平台，您尚未将其作为标签共享，因此请阅读您的手册页以查看sed的用法。

其次，为了在多行上处理文本，您需要在编辑缓冲区中有多行。您可以在逐步完成文件时将它们附加到保留缓冲区中，然后一次处理它们。这是非常先进的sed用法，比大多数人可以处理的更困难。即使我们可以将一些有用的东西放在一起，它也会像线路噪声一样读取，事后几乎不可支持。

我建议使用awk代替。

#!/usr/bin/awk -f 

# pay attention to are "start of server" line, 
/^[[:space:]]*server {/ { n=1 } 

# increment bracket counter within the server block, 
n>0 && /^[[:space:]]*{/ { n++ } 

# decrement the bracket counter within the server block, 
n>0 && /^[[:space:]]*}/ { n-- } 

# and if we're still within the block, skip to the next line. 
n>0 { next } 

# short-hand for "print the current line" 
1 

注意，条件中包含n>0而不仅仅是n因为AWK认为任何非零值评价为“真”。

还要注意，这只适用于每行包含一个squirly括号的文件。我不确定nginx是否需要这样做，但是如果它允许使用} }关闭某个节中的节，请注意上面的脚本不会正确解析该节。

YMMV。未在动物身上测试。可能含有坚果。